Times used to be, a video game player’s library might have been limited to as many piles of cartridges or discs as they could fit at home. But as consumers turn to digital libraries for everything from movies and TV to music, it only makes sense that the gaming industry would follow a similar path. That’s why Microsoft is launching a new monthly subscription service that gives users access to more than 100 downloadable games from its legacy catalog.

Xbox Game Pass will be available later this spring, and offers unlimited access to more than 100 Xbox One and backwards-compatible Xbox 360 games for $9.99 per month.

That’s a smaller library than PlayStation Now’s selection of about 450 games. Depending on how you pay for for PS Now, it’s either a lot more expensive or slightly less expensive than Xbox Game Pass. A monthly subscriber pays twice as much ($19.99). Someone who buys PS Now in three-month chunks pays 50% more ($45) than a Game Pass customer for the same period. If you’re willing to fork over for an entire year of PS Now, the $100 annual fee actually comes out to less per month than the Xbox service.

Microsoft isn’t coughing up a complete list of which games will be in the catalog, however, saying instead only that Halo 5: Guardians, Payday 2, NBA 2K16, and SoulCalibur II will be among those available when the service launches “later this spring.”

Additional games will cycle in and out regularly, Microsoft says, but major releases likely will take some time to hit the platform.

Another area where Game Pass differs from PS Now is the ability to download games. With Game Pass, you’ll be able to play downloaded games as long as your subscription is current, but if you want to keep playing them beyond that, or access a title after it cycles out of availability, you’ll have to buy it. However, Games Pass customers will be able to receive a discount on the purchase price.”

Before XBox Game Pass launches to the broader community in a few months, Microsoft says it will be testing the service with “select members of the Xbox Insider Program in the Alpha Preview ring starting today with a very limited number of titles,” adding that Xbox Live Gold members will receive access to the service before it launches on a wider basis as well.